The present invention relates to a device for use in formers which comprise a plurality of dies arranged in a horizontal row and punches disposed in front of the respective dies in opposed relation thereto and movable toward and away from the dies for producing bolts, nuts or various other parts by plastic press work. The device is adapted so that when the punch on the ram side of the former needs to be replaced due to wear or damage, the punch is fully automatically removed and replaced by a new punch in a sequential operation.
Horizontal formers of the multi-stage type are known which comprise a plurality of dies arranged in a horizontal row with punches opposed to the respective dies and movable into striking contact with a metal material for plastic press work. The former usually has four to five pairs of punches and dies for successively striking the material with a high pressure in repetition by the reciprocating movement of the ram. Accordingly, the tools for use in the former can become very markedly worn or damaged. The punches wear more greatly than the dies. A trimming punch (or trimmer punch) and cavity forming punch, especially, undergo several times greater wear than other punches; such that only the trimmer punch or cavity forming punch must be replaced frequently when other punches have not worn substantially.
For example, Unexamined Japanese Patent Publications SHO 57-177842 and SHO 63-281739 disclose devices for use with such horizontal formers of the multi-stage type for replacing a tool using a robot.
The conventional devices have a robotic chuck reciprocatingly movable over a specified section for executing a sequence of replacement procedure, starting with the removal of the old tool and ending with the setting up of a new tool. The replacement therefore requires a considerably long period of time during which the machine needs to be entirely held out of operation. The actual operation of the machine then encounters a serious problem with respect to the work efficiency and productivity. Furthermore, a large apparatus, such as a crane, for robot travel must be provided for one former, necessitating a large space and entailing other problems in respect of cost, etc.